Negative kerr nonlinearity of graphene as seen via chirped-pulse-pumped self-phase modulation Vrije Universiteit Brussel
We experimentally demonstrate a negative Kerr nonlinearity for quasiundoped graphene. Hereto, we introduce the method of chirped-pulse-pumped self-phase modulation and apply it to graphene-covered silicon waveguides at telecom wavelengths. The extracted Kerr-nonlinear index for graphene equals n(2,gr) = -10(-13) m(2) = W. Whereas the sign of n(2,gr) turns out to be negative in contrast to what has been assumed so far, its magnitude is in ...